Asphalt shingles – moss and lichen

Causes

Insufficient cleaning

The roof remains damp due to overhanging branches

Listed under: Roof, cladding, moisture, roof cladding, asphalt shingles

Cause

Insufficient cleaning

Repair

  • clean roof regularly with a solution of 1 part household bleach to 4 parts water to restrict moss growth; brush on with a stiff broom or wire brush. Do not use where the water is collected for drinking.
  • nail a 150 mm wide copper strip along the roof ridge; alternatively install copper ridge flashing – the copper oxide solution produced by the rain is toxic and will restrict moss growth. Check that copper is compatible with adjacent building materials such as guttering and downpipes.
  • Do not waterblast as this can force water up between the tiles and damage the chip surface.

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Cause

The roof remains damp due to overhanging branches

Repair

  • cut  back any overhanging branches to reduce the likelihood of debris on the roof
  • clean roof regularly with a solution of 1 part household bleach to 4 parts water to restrict moss growth; brush on with a stiff broom or wire brush. Do not use where the water is collected for drinking.
  • nail a 150 mm wide copper strip along the roof ridge; alternatively install copper ridge flashing – the copper oxide solution produced by the rain is toxic and will restrict moss growth. Check that copper is compatible with adjacent building materials such as guttering and downpipes.
  • Do not waterblast as this can force water up between the tiles and damage the chip surface.

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